Means for unidirectional photo enlarging and reducing



J. K. BRUCE 3,115,081

MEANS FOR uummscnomr. PHOTO ENLARGING AND REDUCING 2 Sheets-Sheet 1 Dec. 24, 1963 Filed Oct. 10, 1960 Nu lllIE Q N! \N N Qb 1 N a R NM llllllllll 11L llllllllllllllllllllll IIIIIIIIIIII: Q I l lllll I'll IIIT l I I I I I I l l I I I I I l 1 I I I l 1 I l 1 I 1 I I l l I I Ill N m mm u mm 1 \M IHHHHHH I I I I I H H U IU L I I I I IH H l l l lU l U l l l lU l l l l Hl HH U l l l lHH H- R Mm v Q X Q i Dec. 24, 1963 J. K. BRUCE MEANS FOR UNIDIRECTIONAL PHOTO ENLARGING AND REDUCING Filed Oct. 10, 1960 ill 2 Sheets-Sheet 2 INVENTOR.

United States Patent 3,115,6ll MEANS FIQR UNIIDERMITEUNAL PHUIG ENLARGENG AND REDUCING John K. Brute, La Verne, Caiitfi, assigner to Albert Van Luit d: Cd, Los Angeles, Calif. Filed ()ct. ill, that), fier. No. 61,736 1 Claim. (G. @575) The invention relates to method for making a photographic print of unidirectionally proportionally ditterent dimensions than the dimensions in the same direction of a variably transparent positive from which the print is made, and to apparatus for practicing such method.

The invention solves a problem of critical importance in the wallpaper industry with respect to Wallpaper produced by rotogravure printing, that is, a wallpaper produced by printing with etched cylindrical rollers of a rotary printing press.

Wallpaper companies search far and wide on a worldwide basis for acceptable designs and patterns to be used for wallpaper. When such a design is found, it is necessary to reduce or enlarge its width and length proportionally so that its length, or even multiples thereof, will equal the circumference of a standard rotogravure roller and its width will conform with standard lengths of rotogravure rollers and standard widths of Wallpaper. Conventional photo enlarging and reducing equipment may be used to change the dimensions of the design to approximately those desired but often cannot be used to obtain the exact dimensions desired, because usually the length and width of the design must be changed different amounts which are not proportional to each other, whereas the conventional equipment changes the dimensions of the design proportionally in all directions. The final change of length and width of the design so that the design will conform with rotogravure roller dimensions and conventional wallpaper widths is normally but a small fraction of an inch and has presented a serious problem in the industry.

This problem has been solved in the past through a meticulous process of physically cutting and piecing the design by hand to produce the required length and width thereof. The disadvantages of this solution of the problem are obvious. It not only is time consuming and expensive, but the cut and pieced design may have a slight patchwork appearance, and for some complicated ornate designs it cannot be used at all.

The invention solves the problem through method and apparatus for making a photographic print of unidirectionally different proportional dimensions than the dimensions in the same direction of a variably transparent positive of the design from which the print is made. Through use of the method and apparatus twice for the same design in perpendicular directions, the design is unidirectionally enlarged or reduced in each direction independently of the enlargement or reduction in the other direction to produce a finished print of the design of proper dimension in each direction to conform with the circumference and length of the rotogravure roller and with standard widths of Wallpaper. This print is then etched on the rotogravure roller in conventional manner.

After a variably transparent positive of the design is obtained through conventional photographic processes, the method is practiced by printing the positive on lightsensitive film with a source of light which illuminates only a discrete extent of the positive while there is relative motion of the positive and the film and of the positive and the source of light simultaneously in parallel directions. The discrete extent of the positive which is illuminated by the light at a given instant extends in a direction parallel to the directions of relative movement.

ice

As a consequence of the relative motions, an extent of film is exposed in the direction of the relative motions which is different than the illuminated extent of the positive in the same direction. This results in a print of the design with dimensions in the direction of relative motions which are proportionally reduced or enlarged, as the case may be, relative to the corresponding dimensions of the transparent positive. Through proper selection of the relative velocities, the dimensions of the positive may be unidirectionally proportionally reduced or increased Within a range of an inch or two. To effect the relative motions, the transparent positive may be stationary and the film and the source of light moved with respect thereto. This is the preferred form of the method. Alternatively, the relative motions of the method may be obtained by holding the source of light in stationary position and moving the positive and the film with respect thereto, or by holding the film in stationary position and moving the source of light and positive with respect thereto, or by moving the film, source of light, and positive, in each case there being the requisite relative velocity of the source of light and the positive and of the film and the positive.

Apparatus to practice the preferred form of the method of the invention includes means for moving light-sensitive film to be exposed to light through a variable transparent positive print of the design, means for exposing to light a discrete extent of the film in the direction of its movement, means for moving the means for exposing in a direction parallel to the direction of movement of the film so that discrete portions of the film in the direct-ion of movement are successively and continuously exposed, means for positioning the positive in the stationary position intermediate the film and the means for exposing, means for preselecting the velocity relative to each other of the means for exposing and the film, and means for operating simultaneously the means for moving the film, the means for exposing, and the means for moving the means for exposing.

The invention will be fully understood from a reading of the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a plan view of a preferred embodiment of apparatus for practicing the preferred form of the method of the invention;

Fl G. 2 is a fragmentary elevation view of the apparatus shown in FIG. 1 looking along the line 22 in FIG. 1;

FIG. 3 is a schematic enlarged vertical sectional view illustrating the operation of the apparatus;

FIG. 4 is a sectional view along the line 4-4 in FIG. 1;

FIG. 5 is an enlarged elevational view of a portion of the apparatus looking along the line 5-5 in FIG. 4; and

FIG. 6 is a schematic wiring diagram of the apparatus.

The method of the invention comprises generically the step of moving simultaneously relative to each other at constant velocity in parallel directions both (a) a variably transparent positive from which a print is to be made and light-sensitive film to be photographically exposed through the positive and (b) the positive and a source of light which illuminates a discrete extent of the positive in the direction or" relative movement. The movements of the source of light relative to the positive and of the film relative to the positive result in exposure of a different extent of the film in a direction parallel to the directions of the relative motions than the extent of the positive illuminated in the same direction, depending upon the magnitude of such relative velocities and their directions. For example, if the positive is stationary and the velocity of the source of light relative to the positive is a constant ten units per second in one direction and the velocity of the film relative to the positive is a constant one unit per second in a parallel but opposite direction, the illumination of. ten units of the positive by the source of light will result in exposure of eleven units of the film, because the film will have displaced one unit in the opposite direction from the direction of displacement of the source of light during the time the source of light displaces ten units to illuminate the ten units of the positive and such displacements, being in opposite directions, will add, thus effecting a unidirectional increase in the direction of movement of the dimensions of the positive as printed on the film which is proportional in all respects because the velocities of the source of light and the film are simultaneous and constant. If the velocities of the source of light and of the film relative to the stationary positive are the same as in the above example but in the same, rather than opposite, directions, the illumination of ten units of positive by the source of light will result in exposure of only nine units of the film, because the film will have dis placed one unit in the same direction as the direction of displacement of the source of light during the time the source of light illuminates the ten units of the positive and such displacements, being in the same direction, will subtract, thus effecting a unidirectional decrease in the direction of movement of the dimensions of the positive as printed on the film which is proportional in all respects because the velocities of the source of light and of the film are simultaneous and constant. The relative movements of the positive and the source of light and of the positive and the film are planar, rectilinear and parallel, although they may be curvilinear if the parallel relationship is maintained. As explained in the introductory portion of the application, the relative velocities may be effected through a stationary positive and moving the film and light with respect thereto, or through a stationary light and moving the positive and film with respect thereto, or through stationary film and moving the positive and light with respect thereto, or through moving the film, light, and positive. The preferred form of the method is practiced with a stationary positive and moving the source of light and the film simultaneously in parallel directions.

The preferred form of the method includes the following steps: First, positioning stationarily a variably transparent positive which is to be printed on light-sensitive film. The positive is so positioned in planar orientation, although it may be positioned in curved or other orientation if the film and the source of light are moved in paths parallel to the orientation of the positive. Second, moving at constant preselected velocity adjacent to one side of the positive light-sensitive film to be exposed through the positive. The movement of the film is parallel to the positive. If the positive is positioned planarly, the film is similarly positioned planarly and is moved rectilinearly. Third, moving simultaneously with the movement of the film a source of light on the side of the positive opposite the side thereof adjacent to the film which illuminates a small preselected discrete extent of the positive in a direction parallel to the direction of movement and which illuminates the entire width of the positive in a direction at right angles to such direction of movement to photographically expose the film through the positive. The movement of the source of light is parallel to the movement of the film and is at constant preselected velocity. If the film is in planar orientation, the source of light moves rectilinearly in a plane parailel thereto. The movement of the source of light and film may be in the same direction or in opposite directions, depending on Whether the print is to be shortened or lengthened, as explained above. A specific example of practice of the preferred form of the method with a form of apparatus for practicing same is given below.

An illustrative form of apparatus for practicing the preferred form of the method is illustrated in the drawings. Referring to FIG. 1, l0 designates a support siirface. The support surface ltl is planar and is supported on legs in the manner of a conventional table. Rack gears 11 and 12 are fixed to the support surface it The rack gears are parallel and extend the full width of the support surface.

An elon gated housing 13 extends between the rack gears at right angles thereto. At each end of the housing is a pair of pinions or gear wheels which mesh with the rack gear at that end, indicated at M and 15 at the left end of the housing in FIG. 1, and 16 and 17 at the right end of the housing. The pinions lid, 15 and l6, 17 are rotatably mounted on the housing so that the housing can be moved only rectilinearly in either direction in a direction parallel to the parallel extent of the rack gears. Each pinion has a concentric hub which rolls on a raised portion of the rack gear to carry the weight of the housing and permit smooth movement thereof with proper meshing and no binding of the pinions and rack gears, such as the hub 18 on the pinion l5 and the raised track 19 on the rack gear 12.

At the right end of the housing, as shown in FIGS. 1 and 2, the shaft which rotatably mounts pinion 16 on the housing protrudes at 2 1 beyond the rack gear 11. A sleeve 21 rotatably mounts on the shaft extension 26 a base 22. As shown in FIGS. 1 and 2, a pair of spaced flanges 23 and 2 4- are fixed to the base 22 and extend upwardly therefrom in parallel relation to each other. Journaled in the flanges 23 and 24 is a drive shaft 25 to which a drive pinion 26 is fixed for rotation therewith. The drive pinion 2 6 meshes with the pinion 17 on the housing so that when the drive shaft 25 is rotatively driven the drive pinion 2.6 rotatively drives the pinion 17 to move the housing. Since the base 22 is rotatably mounted on the shaft extension Zil, it may be lifted to rotate it about such shaft to disengage the drive pinion Z6 and pinion l7 and thus permit the housing to be moved along the rack gears by hand to a desired position, at which the base may be lowered to again mesh the drive pinion 26 and pinion 1'7. Mounted on the base 22 is a constant speed electric housing motor 2'7. The motor 27 is preferably a synchronous motor, and it is wired for rotation of its armature shaft 2.3 in either direction. A motor pinion 29 is fixed to the shaft 23 of the motor for rotation therewith and, through a reduction drive schematically shown in FIGS. 1 and 2, rotatively drives the drive shaft 25 to move the housing at a velocity of on the order of six inches per minute. As schematically illustrated, the reduction drive consists of gearing comprising a countershaft 3t journaled in the flanges 23 and 24 to which is fixed a reduction gear wheel 31 which meshes with the motor pinion 29. The countershaft Eitl extends beyond the flange 24 and on its cantilever portion is removabiy fixed a small gear Wheel 32 which meshes with a second reduction gear Wheel 33 removably fixed to a cantilevered portion of the drive shaft 25. It is to be understood that any conventional reduction drive between the motor 27 and the drive shaft 25 may be utilized to produce the desired relatively slow velocity of movement of the housing 13.

Means for varying and preselecting the velocity at which the housing will be moved by the housing motor 27 is provided. The range of such velocities which may be preselected is on the order of four to twelve inches per minute. This means is schematically illustrated in FIGS. 1 and 2, and consists of the cantilevered portions of the countershaft 3t) and drive shaft 25 with the gears 32 and 33 removably fixed thereto. With this structure, the gears 32 and 33' may be removed and replaced by a selected pair of meshing gears with a ratio which will produce the desired velocity of the housing 13, such pair of gears being determined in conventional manner obvious to those with ordinary skill in the art. It is to be understood that any conventional means for varying and preselecting the velocity within the above range at which the housing is moved by the housing motor 27 may be utilized, in particular, a conventional electrical speed regulator interposed in the electrical circuit which operates the housing motor 27 may be used. Thus, it is apparent that the housing is operable to be moved rectilinearly in a direction parallel to the parallel extent of the rack gears 11 and 12 at constant preselected velocity.

As best shown in FIG. 4, the housing 13 has an aperture communicating between the exterior of the housing and an interior space 44 therein. The aperture 40 is a slit which extends substantially the entire length of the housing 13 which parallel sides 41. and 42 oriented at right angles to the parallel extent of the rack gears 11 and 12 and to the direction of movement of the housing '13. The aperture 40 is of small width in a direction parallel to the direction of movement of the housing 13, and such width is constant throughout the length of the aperture, for example, a uniform width of on the order of oneeighth inch. The parallel sides 41, 42 of the aperture extend at substantially right angles to the plane of the support surface lift from the exterior to the interior of the housing. The sides are of substantial length, for example, on the order of one and one-half inches, such length functioning to reduce diffusion of light in order that only a small finite width is illuminated through the aperture from a light source mounted in the space 44 of the housing. The light source consists of a conventional fluorescent illuminating tube 43 which is mounted in the interior space 44 of the housing 13 over the aperture 4t} and which extends substantially the full length of the aperture. The interior space 44 of the housing and the surfaces of the sides 41 and 42 of the aperture, as Well as the support surface It), are all preferably of a dull black finish to reduce to a minimum reflection and diffusion of light from the aperture.

A pair of belt rollers 45 and 46 are rotatably mounted on the support surface 10 along each side thereof. The axes of the belt rollers extend at right angles to the parallel extent of the rack gears 11 and 12 and the peripheries of the rollers are even with or slightly below the plane of the planar support surface It}. A flexible but inextensible belt 5ft extends across the support surface it over the belt rollers 45 and 46 and down from such rollers on each side of the support surface. The belt htlslides on the support surface lit and is maintained in planar configuration while on the support surface as a result of the planarity of the support surface and the structure described below. As best shown in FIG. 4, one end of the belt has a weight Sll fixed to it which extends uniformly the full width of the belt. The other end of the belt has a weighted yoke 52 fixed to it which extends the full width of the belt uniformly on each side of the center of the belt. The two weights 51 and 52 function to maintain the belt in evenly tensioned condition so that it does not ripple and maintains contact with the planar support surface 10, with the result that the belt is maintained in planar orientation as it is slid across the support surface M. The belt is of dull black color for the reason explained above for the similar color of the support surface It).

A pull wire 53' is attached at 54 to the yoke 52. The point of attachment 54 of the pull wire to the yoke is located centrally of the yoke and of the belt 5t} so that pulling forces exerted on the pull wire 53 are not unevenly applied to the belt The pull wire 53 is flexible and is inextensible. The inextensibility of the pull wire and belt facilitate constant velocity motion of the belt as described below. The pull wire '53 extends around a pulley wheel 55 rotatably mounted on the undercarriage of the support surface lit) and extends therefrom to a sprocket chain 56 to which it is connected. Thus, when the pull wire 53 is pulled, the belt St) is thereby moved, and its portion sup ported on the support surface ltl moves planarly as described above and also, because the axes of the belt rollers are perpendicular to the parallel extent of the rack gears and the belt its tensioned over their peripheries, rectilinearly in a direction parallel to the parallel extent of the rack gears 11 and 12.

As best shown in FIG. 5, a base plate 57 is mounted on the supporting undercarriage of the support surface 10, and a pair of parallel spaced flanges 58 and 59 extend upwardly therefrom. A sprocket shaft 60 is journaled in the flanges 58 and 59. A small diameter sprocket wheel 61 is attached to the shaft as for rotation therewith. The teeth of the sprocket wheel 61 mesh with the sprocket chain 56. The sprocket chain 56 extends over the sprocket wheel of in meshed relation therewith and downwardly to a free end to which is fixed a weight 62. The Weight -62 maintains engagement between the sprocket Wheel and the sprocket chain without play or backlash therebetween. Through this arrangement, the belt 50 may be moved as described above through rotation of the sprocket shaft 60, and, when it is desired to move the belt large amounts to reset it, the sprocket chain 56 may be lifted from the sprocket wheel oil and the belt so moved by hand to a desired position where the sprocket chain and sprocket wheel are again engaged. It is apparent that means other than that described above maybe used to move the belt 50.

A constant speed electric motor 63, preferably a synchronous motor, is mounted on the base 57. The motor 63 is operatively connected to the sprocket shaft 66 to rotatively drive such shaft at such speeds that the belt 5ft is moved at a constant velocity of on the order of oneeighth inch per minute. This connection may be effected through any of many conventional types of reduction drives. A reduction drive is schematically illustrated in FIGS. 2, 4, and 5. As best shown in FIGS. 4 and 5, a countershaft 64 is rotatably journaled in the flanges 58 and 59. Fixed to the countershaft 64 for rotation therewith is a large diameter reduction gear wheel 65 which meshes with a small diameter pinion gear 66 fixed to the shaft of the motor 63. The countershaft 64 cantilevers beyond the flange 59, and a small diameter pinion gear 67 is removably fixed to the cantilevered portion. The sprocket shaft as cantilevers beyond the flange 59 in the same manner as the countershaft 64, and a large gear wheel as which meshes with the small gear wheel 67 is removably fixed to the cantilevered portion of the sprocket shaft. Through this reduction gearing, the motor as rotatively drives the sprocket shaft 6ft and sprocket wheel til at the necessary slow speed. The speed at which the sprocket shaft 60 is rotatively driven can be selectively determined by means of removing the gears 67 and 68 and replacing them with meshed gears of the proper ratio to produce the desired rotational speed of the sprocket shaft 61; alternatively, conventional speed selecting means may be employed, such as an electric speed regulator in the circuit which operates the motor 63.

Light-sensitive film to be photographically' exposed through a variable transparent positive is releasably fixed to the belt 5% for movement therewith. As shown in FIG. 1, the film 7r? is so fixed by means of adhesive tabs, such as the tab 71. The film is flexible. With this arrangement, the film 7ft conforms with the orientation and movement of the belt 50, so that the film moves rectilinearly and planarly in a direction and in a plane parallel to the direction and to the plane of movement of the housing 3d at preselected constant velocity responsive to movement of the belt 5ft in such manner with the means described above.

A conventional variably transparent positive 72 is posi tioned stationarily and planarly adjacent to the film 7t) and between the film and the housing 1.3. As illustrated in FIG. 1, this is accomplished by releasably attaching the positive 72 to a rigid planar transparent member 73, such as a piece of plate glass or the like, by means of adhesive tabs, such as the tab 74. The transparent plate '73 and the positive 72 removably attached thereto are, as a unit, placed over the film and held in stationary position by means of stops 75 and '76 engaging the edge of the plate.

The spatial relationship of the belt 50, film 70, positive 72, and transparent plate '73 are best shown in FIG. 3, which is an enlarged vertical section through such members. As shown in FIG. 3, the planar support surface It) supports the flexible belt 50 thereon in slidable planar hearing engagement. The film 7 assumes the same configuration and orientation as the belt 51 In sliding bearing contact with the film 70 is the transparent positive 72 Which is held in stationary planar position by the transparent member '73. The transparent member 73 is planar and has substantial weight so that it presses the positive into slidable bearing contact with the film and causes the positive as well as the film to assume a planar configuration. Located immediately adjacent to the transparent member 73 is the housing 13 with its light aperture 40 extending down as close as possible to the surface of the member 73 for minimal reflection and diffusion of light emanating from the aperture to print the positive on the film. The belt normally moves in one direction only, as indicated with the arrow 81. The housing 13 may selectively move in either direction, depending on the direction of rotation of its driving motor 27, as indicated with the arrow 82. i

The housing motor 27, belt drive motor 63, and light 43 are wired in conventional manner so that all three may be operated simultaneously. An illustrative wiring diagram to achieve such purpose is shown schematically in FIG. 6. The belt drive motor 63 is connected directly to a source of current with a switch 83 interposed in the circuit. The source of light 43, preferably a fluorescent tube, is wired in conventional manner with ballast 84 and automatic starter 85 through a switch 86. The housing drive motor 27 is connected in parallel with the circuit for the light with a two-way switch 87 so that completing a circuit to the motor through one pole of the switch operates the motor in one direction of rotation and con pleting the circuit to the motor through the other pole operates the motor in the opposite direction of rotation. Consequently, when the switches $3, 86, and 87 are all closed, the housing motor 27, belt drive motor 63, and light 43, all operate simultaneously.

Operation of the above described apparatus to perform the method of the invention will now be described. Assume that through conventional photo reduction methods a variably transparent positive measuring 26.5 by 24 inches has been obtained. Assume that in order for the length of the positive to conform to the circumference of the rotogravure roller, the length must be increased from 26.5 to 26.875 inches and that for the width of the positive to conform with a standard width of wallpaper and the length of the rotogravure roller, the width must be reduced from 24 to 23.5 inches. This calls for a unidirectional extension of length of 0.375 inch and a unidirectional contraction of width of 0.50 inch.

Assume that the belt drive motor, through the reduc tion drive, is set up to move the belt in the direction indicated with the arrow '81 in FIG. 3 at a constant unidirectional velocity of 0.125 inch per minute. This velocity may be picked arbitrarily within the limitations described below with respect to proper exposure of the film.

Starting with the extension of 0.375 inch in length of the print of the positive, it is apparent that the belt and the film attached thereto, moving to the left in FIG. 3 at a velocity of 0.125 inch per minute, will displace to the left 0.375 inch in three minutes. If, during this period of three minutes, the displacement of the housing 13 relative to the stationary positive is the entire 26.5 inch length of the positive, and the direction of such displacement of the housing is to the right in PEG. 3, the resulting length of film exposed to light from the aperture in the housing will be 26.875 inches, because the displacements of the film and of the housing are in opposite directions and therefore add relative to each other. In order for the housing to displace the 26.5 inches in the time period of three minutes while moving at constant velocity, it is apparent that such velocity relative to the positive must be 8.833 inches per minute. Accordingly, the velocity at which the housing is moved by the motor 27 is selected at 8.833 inches per minute.

Checks of the velocity of the housing 13 may be accomplished by means of a graduated measuring scale 99 fixed to the support surface 10* and index pointers 9]. and 92 fixed to the housing and aligned with the indicia on the scale 3%. With a stop watch the displacement of the housing for a given period, and hence its velocity, may be determined readily with the scale and index pointers 9t and 92. if the means for preselecting the velocity of the housing 13 is not susceptible to preselection of exact velocities, such as might be the case with the above described removable gears 32 and 33, this may be compensated for without disrupting the practice of the method by preseleoting a slightly greater velocity of the housing 13 than desired and stopping the movement of the housing 3.3 at, for example, the third points of the positive for a very short duration of time so that the total displacement of the housing 13 during the three minute period is the desired 26.5 inches. The light 23 is turned off during the stopped period to avoid over exposure of the film. This stopping of the housing l3 with a turning oif of the light 2 3 during the stopped period but without turning off the belt drive motor 63 may be accomplished with the circuit diagram illustrated in FIG. 6 by merely opening the switch 86.

With the velocity of the housing 13 thus selected, the room is darkened, the film to be exposed is releasably fixed to the belt by means of tape tabs, and the variably transparent positive to be illuminated for exposure of the film is similarly releasably attached to the member 73 by means of tape tabs. The member 73 with the positive is then laid over the film with the positive and the film in sliding contact as described above. The drive pinion 26 and pinion 17 are disengaged by rotating the base 22 as described above, and the housing 13 is then moved by hand to a position which places its light aperture 40 to the left of the left edge of the positive in FIG. 3. The drive pinion 26 and pinion 17 are then meshed. The apparatus is now ready for operation to practice the method.

The housing motor 27, belt drive motor 63, and light 43 are all turned on simultaneously, the switch 87 for the housing motor 27 being closed in such manner to cause the housing motor to rnove the housing 13 in a direction to the right in FIG. 3. A small portion of the film is wasted during the period of time that the light aperture 4% of the housing takes to reach the left edge of the positive, but when the light aperture reaches the left edge of the positive, the positive is thereafter exposed on the fi-lm while the film and the light aperture are moving rectilinearly simultaneously in opposite parallel directions. The entire 26.5 inch length of the positive is so exposed. The machine is then turned oif and the exposed film developed. This will result in a print of the positive with a lengthwise dimension of 26.875 inches and with the pattern of the design on the positive enlarged proport-ionately and unidirectionally on the print, as described above in connection with the method of the invention.

The print thus made, while it is the desired 26.875 inches in length, will be 24 inches wide, as was the positive. Consequently, a second variably transparent positive is made of this print and is positioned on the member 73 with its 24 inch dimension extending in the direction of movement of the housing 13 and belt 50. The change desired of the 24 inch dimension is a reduction of 0.50 inch. From the belt velocity of 0.125 inch per minute to the left in FIG. 3, it is apparent that the belt and the film attached thereto will displace to the left 0.50 inch in four minutes. If within this four minute period the displacement of the housing 13 relative to the stationary positive is the entire 24 inch extent of the positive and such displacement of the housing is in a direction to the left in FlG. 3, it is apparent that the displacement of the housing relative to the film during such four minute period will be only 23.50 inches, because the simultaneous displacements of the housing and the film will be in the same direction and therefore will subtract. As a consequence.

the entire 24 inch extent of the positive will be exposed on the film, but the resulting print on the film Will be only 23.50 inches in extent in the same direction. The necessary velocity of the housing relative to the stationary positive is calculated as described above for the lengthening of the 26.50 inch dimension and Would be 6 inches per minute in a direction to the left in FIG. 3. The method is then carried out in the same manner as described above for the lengthening, except that the light aperture is started from a position to the right of the right edge of the positive in FIG. 3 and displaces to the left rather than to the right. The dimensions of the resulting print Will be the desired 23.50 by 26.875 inches with the pattern of the design correspondingly proportionally changed in size. The print is then transferred to the rotogravure roller in conventional manner.

Since the film is exposed through the positive, the aspect of proper exposure time of the film with the light source 43 arises. Normally this is not a critical factor. The exposure time of the film is determined by the velocity of the light aperture 40 relative to the film in relation to the width in the direction of such movement of the aperture. Thus, as described above for the lengthening of the 26.5 inch dimension of the positive, if the film is moving 0.125 inch per minute to the left in FIG. 3 and the aperture 40 is moving 8.333 inches per minute to the right, the velocity of the aperture relative to the film is 8.333 plus 0.125, or 8.958 inches per minute, and if the width of the aperture is 0.125 inch, the time required for a displacement of 0.125 inch of the aperture relative to the film is the exposure time of the film. This time period is computed from the aperture width, 0.125 inch, divided by the velocity of the aperture relative to the film of 8.958 inches per minute, the exposure time thus effected is not proper for the film, a faster or a slower film in terms of its light sensitivity may be used, or through suitable apparatus the Width of the aperture 40 may be changed, with a smaller width decreasing the exposure time for given velocities of the film and light aperture, or the velocity of the film may be changed with corresponding necessary change of the velocity of the light source. For example, if in the above example in connection with the 26.5 inch dimension of the positive, the velocity of the belt is increased from 0.125 to 0.250 inch per minute to the left in FIG. 3, the velocity of the light source to the right in FIG. 3 must be 17.666 inches per minute, which for an aperture Width of 0.125 inch results in an exposure time for the film of 0.4186 second.

It is to be understood that the apparatus described above is an illustrative form of apparatus which may be used to practice the preferred form of the method. Many other arrangements of apparatus may be used to practice the method. For example, the light-sensitive which equals 0.8310 second. If

film could be mounted on a rotatable cylindrical drum and held thereon by a vacuum plate surface of the drum. The positive could be mounted on a concentric coaxial juxtaposed transparent sleeve surrounding the drum and rotatable about the same axis as the drum. The light source then could be mounted in fixed position over the sleeve radially of the common axis of the drum and sleeve. To practice the method, the drum and the sleeve could be rotated in the same direction or in opposite directions at preselected constant velocities. Alternatively, the sleeve could be stationary and the light source mounted on arms to rotate about the axis of rotation of the drum. Many other forms of apparatus to practice the method would be apparent to one skilled in the art.

I claim:

A unidirectional photo enlarger and reducer comprising a planar support surface, parallel rack gears fixed t0 the support surface, a housing extending between the rack gears, gear wheels rotatably mounted on the housing meshing with the rack gears, whereby the housing can move only rectilinearly in a direction parallel to the parallel extent of the rack gears, an elongated aperture in the housing adjacent the support surface communicating between the exterior and the interior of the housing, said aperture having parallel sides extending between the rack gears at right angles thereto, a source of light within the housing and surrounded thereby for illuminating through the aperture in the housing, a first motor on the housing, means for rotatively driving the gear wheels on the housing at constant speed with the first motor, means for preselecting the speed at which the first motor will rotatively drive the gear wheels, a belt member supported movably and planarly on the support surface between the rack gears, 21 second motor, means for moving the belt rectilinearly in a direction parallel to the direction of motion of the housing at constant speed with the second motor, means for preselecting the speed at which the second motor will move the belt, light-sensitive film releasably fixed to the belt, whereby the film moves with the belt, a variably transparent positive to be photographically printed on the film disposed between the film and the housing, means for holding the positive in stationary planar position, and means for operating simultaneously the first motor, the second motor, and the source of light, whereby the motion of the housing relative to the film results in exposure of an extent of film in the direction of motion different than the illuminated extent of the positive in the same direction.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 115 O81 December 24 1963 John K., Bruce It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 9 lines 26 and 27 for "8.333" each occurrence read 8.833

Signed and sealed this 26th day of May 19640 ISEAL) meet:

ERNEST W. SWIDER EDWARD J. BRENNER Xttesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 115,081 December 24, 1963 John K. Bruce It is hereby certified that error appears in the above numbered patent requiring correction and that the said'Letters Patent should read as corrected belo* Column 9 lines 26 and 27 for "8.333",, each occurrence, read 8.833

Signed and sealed this 26th day of May 1964.,

CSEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Commissioner of Patents Ittesting Officer 

